Technical Field
The technical field generally relates to displaying objects on a screen at a desired visual angle, and more particularly, in one aspect, to systems and methods for displaying optotypes during an eye examination.
Background Discussion
Eye examinations are routinely used to determine the appropriate lens prescription or make other diagnoses for patients. Eye exams have traditionally been performed by optometrists or the like in an office where the test subject is positioned at a set distance from an eye chart displaying optotypes of a known size. The test administrator is able to calculate the perceived size of the optotypes from the perspective of the test subject, and draw conclusions regarding the subject's vision according to the test results. Efforts to translate eye exam procedures from a doctor or technician's office to non-traditional locations such as self-administered tests at home are hampered by the difficulties associated with ascertaining the perceived size of the characters used in the test. Previously proposed solutions such as using measuring tape or counting steps to determine a distance from a computer screen displaying an eye test require additional equipment or steps and may erode a user's confidence in the results, making a test administered out of office less attractive.